Two systems of recombination and replication in E. coli and Lambda will be studied: RecA dependent RNA replication and Lambda-Red mediated recombination. Additional mutants which regulate Rec dependent replication will be sought and their interactions studied. The dnaT and sdrT genes will be cloned and their products isolated. Using Mud insertions, the transcription of these genes will be analyzed. Intermediates in Rec dependent replication will be studied in vitro, and the role of this replication system in mutagenesis will be further analyzed. Using a "Hyper-Red" recombination prone DNA sequence, inserted into a Lambda vector, we will study Red mediated deletions and recombination. This system will be used to develop an in vitro assay system of Red recombination, driven by concomitant DNA replication. This system may be a prototype for somatic recombination in animal cells and will be used to assay for the presence of animal cell recombination enzymes.